Method of hard surfacing metal bodies



Oct. 14, 1941. JANCQ 2,258,894

METHOD OF HARD SURFAGING METAL BODIES Filed May 15, 1940 Mo 7,4,4JANC'O.

mvsu-ron BY :3

/ Armxezgi Patented Oct; 14, 1941 UNITED STATES PATENT o-FFIcE NathanJanco, Houston, Tex, assignor to Reed Roller Bit Company, Houston, Tex,a corporation of Texas Application May 13, 1940, Serial No. 334,848

This invention relates to the hard surfacing of metal bodies. Thegeneral object of this invention is to provide a method whereby metalFig.3 is anew similar to Figs. 1 and 2 but showing the hard surfacing ofa different formof metal body.

Referring to the drawing, the numeral l in Fig. 1 indicates a metal bodywhich in this instance is in the form of a toothed cutter for use ondrill bits or the like. It will be understood that this invention is notlimited to employment with toothed cutters but may be employed inconnection with any metal body on which hard surfacing is required.

In the present instance the metal body is hollow having an opening 2therethrough and on its outer surface has teeth 3. It is necessary inthe case of such a cutter that the teeth be provided with customary hardsurfaces and such surfaces have been in the past provided by theembedding of particles of some hard material, such as tungsten carbide,into the metal of the teeth themselves.

Surrounding the cutter just referred to is an electric induction coil 4'which may be carried within a housing 5 or the like.

through which air or some other material may be blown for a purposepresently to be described.

.The bottom of the housing isfalso provided with an opening 0 so thatsuch air or the like may. escape therethrough. The induction coil isprovided with leads 9 by which it may be connected to a source of highfrequency electric current.

It will be noted that the inner conformation of the induction coil issuch as to substantially conform both in size and shape to the outercontour of the cutter orother body, which is to be treated.

In the practice of this invention, the metal A cover 0 is provided forthis housing having a connection .1

material preferably carried in a binder such as resin or some agentwhich will promote the wetting of the particles of hard-surfacingmaterial by the metal of the body being treated when such metal isfused.

After the hard surfacing material has thus been applied to the surfaceof the body to be treated, it is placed in position within the inductioncoil, as shown in Fig. 1, and a source of high frequency alternatingcurrent is connected to the leads 9. The induction coil 4 then acts inthe well known manner as the primary coil of a transformer and inducesan electric current of the same frequency in the metal of the may I.

The high frequency current referred to is of such a frequency that theskin effect as this current passes through'the metal body will cause thecurrent to be concentrated in the surface portions of the body. Theseportions will thus be its surface layer impregnated with the particlesof tungsten carbide or other hard surfacing material and the same willhave been accomplished without the personal factor ordinarily present inany other manner of hard surfacing such metal bodies.

During the heating of the metal body it may be found desirable to blowair or some similar substance through the body by some suitable means,such as the connection I.- This would positively retard anytendency forthe center porand these are not susceptible of being exactly defined.However, in most cases frequencies from 300 cycles per secondupwardly'may be employed and a frequency in the neighborhood of 25,000

body I is coated first with the hard surfacing cycles per second shouldprove eminently satisfactory.

In the modiiled form illustrated in Fig. 2, the induction coil isomitted and instead the housing ll encloses the cutter II, which ispreviously coated in the same manner as above noted and which. is thenplaced in the housing II with an electrode II in contact with one endandanelectrode I3 in contact with the other end of the cutter. It isnoted that the housing II] has a cover It with an inlet I5 for air orthe like in the same manner as illustrated in Fig. 1. It .is also notedthat the electrodes l2 and I3 have openings l6 and i1 therethrough andthat the bottom of the housing I0 has an opening 18 therethrough so thatthe air or the like may pass through the center of the cutter while itis being heated.

In this instance the high frequency electric current, as previouslyreferred to, is connected directly to the electrodes l2 and I3 by meansof the leads l9 and 20 respectively so that the high frequency currentmay be passed directly to the body being heated instead of being inducedtherein as is the case in Fig. 1.

Except as noted, the method carried out in accordance with Fig. 2 is thesame as that described in connection with Fig. 1.

\ In Fig. 3 there is shown a device that is identical in everysubstantialparticular with that shown in Fig. 1 except that the interiorof the induction coil is formed to receive a cylindrical member such asa tool joint 2| or'the like which is to be provided with a hard outersurface. This body likewise has an opening 22 therethrough so that airor the like may be blown through the body while it is being heated.

The housing 23, the induction coil 24, the cover 25, the air inlet 26,and the opening 21 in the lower portion of the housing are in sub-Having described my invention, I claim: 1. A method of embeddingparticles of tungthe metal of said body when fused, passing an electriccurrent through said coated body at a frequency suificiently high toproduce a skin effect, thereby causing the .major portion of the currentto be concentratedin the outer coated surface of said body, continuingthe passage of the high frequency electric current through said bodyuntil the surface of the body which has been coated, and substantiallythat surface only, but not the tungsten carbide, is fused and the fusedmetal has wetted the solid particles of tungsten carbide to embed saidparticles in the surface of the body, whereby said fused body metalconstitutes the sole anchoring means for said particles and thenimmediately stopping the flow of current to permit cooling and hardeningof the fused surface. I

2. A method of embedding particles of tungsten carbide in the outersurface-of a softer metalbody of substantially circular section having abore extending axially therethrough comprising coating the outer surfaceof said body with particles of tungsten carbide carried in a stencarbide in the surface of a softer metal body comprising coating theouter surface of said body with particles of tungsten carbide carriedbinder having the property of facilitating'wetting of the particles oftungsten carbide with the metal of said body when fused, passing anelectric current through said coated body at a frequency sufficientlyhigh to produce a skin effect, thereby causing the major portion of thecurrent to be concentrated in the surface of said body, passing acooling medium through the borein said body to cool the inner portionthereof, continuing the passage of the high frequency electric currentthrough said body until the outer surface of the body which has beencoated, but not the tungsten carbide, is fused and the fused metalhas'wetted the solid particles of tungsten carbide to embed saidparticles in the surfaceof the body, and then immediately stopping theflow of current to permit cooling and hardening of the fused surface.

NATHAN JANCO.

